From 241af1cdbcb58c545c278a523c271bf405d1259c Mon Sep 17 00:00:00 2001
From: Karl Tomlinson <karlt+@karlt.net>
Date: Fri, 27 Oct 2023 07:52:45 +0000
Subject: [PATCH] Bug 1860954 add a conversion operator from
 MediaTrackGraphImpl to Lookup for HashSet.lookup(*graph) r=pehrsons

Differential Revision: https://phabricator.services.mozilla.com/D191920
---
 dom/media/MediaTrackGraph.cpp   | 18 +++++++++++-------
 dom/media/MediaTrackGraphImpl.h |  3 +++
 2 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/dom/media/MediaTrackGraph.cpp b/dom/media/MediaTrackGraph.cpp
index f82f866d0a4a..e4f1a89aa87e 100644
--- a/dom/media/MediaTrackGraph.cpp
+++ b/dom/media/MediaTrackGraph.cpp
@@ -117,12 +117,12 @@ void DeviceInputTrackManager::Remove(DeviceInputTrack* aTrack) {
   }
 }
 
-namespace {
 /**
  * A hash table containing the graph instances, one per Window ID,
  * sample rate, and device ID combination.
  */
-struct GraphLookup final {
+
+struct MediaTrackGraphImpl::Lookup final {
   HashNumber Hash() const {
     return HashGeneric(mWindowID, mSampleRate, mOutputDeviceID);
   }
@@ -131,8 +131,14 @@ struct GraphLookup final {
   const CubebUtils::AudioDeviceID mOutputDeviceID;
 };
 
+// Implicit to support GraphHashSet.lookup(*graph).
+MOZ_IMPLICIT MediaTrackGraphImpl::operator MediaTrackGraphImpl::Lookup() const {
+  return {mWindowID, mSampleRate, mOutputDeviceID};
+}
+
+namespace {
 struct GraphHasher {  // for HashSet
-  using Lookup = const GraphLookup;
+  using Lookup = const MediaTrackGraphImpl::Lookup;
 
   static HashNumber hash(const Lookup& aLookup) { return aLookup.Hash(); }
 
@@ -3600,8 +3606,7 @@ void MediaTrackGraph::AddTrack(MediaTrack* aTrack) {
   MediaTrackGraphImpl* graph = static_cast<MediaTrackGraphImpl*>(this);
 #ifdef MOZ_DIAGNOSTIC_ASSERT_ENABLED
   if (graph->mRealtime) {
-    GraphHashSet::Ptr p = Graphs()->lookup(
-        {graph->mWindowID, GraphRate(), graph->mOutputDeviceID});
+    GraphHashSet::Ptr p = Graphs()->lookup(*graph);
     MOZ_DIAGNOSTIC_ASSERT(p, "Graph must not be shutting down");
   }
 #endif
@@ -3621,8 +3626,7 @@ void MediaTrackGraphImpl::RemoveTrack(MediaTrack* aTrack) {
     if (mRealtime) {
       // Find the graph in the hash table and remove it.
       GraphHashSet* graphs = Graphs();
-      GraphHashSet::Ptr p =
-          graphs->lookup({mWindowID, mSampleRate, mOutputDeviceID});
+      GraphHashSet::Ptr p = graphs->lookup(*this);
       MOZ_ASSERT(*p == this);
       graphs->remove(p);
 
diff --git a/dom/media/MediaTrackGraphImpl.h b/dom/media/MediaTrackGraphImpl.h
index a28171310866..668fcaea3176 100644
--- a/dom/media/MediaTrackGraphImpl.h
+++ b/dom/media/MediaTrackGraphImpl.h
@@ -142,6 +142,9 @@ class MediaTrackGraphImpl : public MediaTrackGraph,
   static MediaTrackGraphImpl* GetInstanceIfExists(
       uint64_t aWindowID, TrackRate aSampleRate,
       CubebUtils::AudioDeviceID aOutputDeviceID);
+  // For GraphHashSet:
+  struct Lookup;
+  operator Lookup() const;
 
   // Intended only for assertions, either on graph thread or not running (in
   // which case we must be on the main thread).